The present invention relates to apparatus for viewing a workpiece at an inaccessible location and performing operations, in particular by means of laser energy, on the workpiece.
It is well-known to employ optical scopes such as borescopes and endoscopes in order to view features in remote and/or inaccessible locations, such as the internal components of a machine. In particular, borescopes are frequently used to internally inspect gas turbine engines. If cracks or other defects are noted in components such as turbine blades, the engine is usually stripped down to provide access to the blade for its repair or replacement.
Since strip down of an engine is a time consuming and therefore expensive process, some systems have been developed which allow a certain amount of remedial work on a defect in a turbine blade to be carried out in situ. For example, U.S. Pat. No. 5,155,941 discloses an optical scope which includes a treatment member in the form of a miniature grinding tool which can be applied to a turbine blade. One problem with this type of system is that the remedial tool must contact the workpiece and since the tool is spinning, it creates a reaction torque.
The present invention provides apparatus for performing an operation on a workpiece at an inaccessible location, comprising a tube having a proximal end and a distal end, the distal end being insertable in use into an inaccessible location; a head flexibly coupled to the distal end of the tube; control means operable to adjust the position of the head with respect to the tube; means to transmit laser energy through the tube to the head and out of the head; viewing means for gathering and displaying an image of the workpiece; tracking means operable to identify and record the position of one or more selected points on the workpiece; a processor operable to actuate the control means to move the head so as to direct laser energy to the selected point or, sequentially, to each of the selected points on the workpiece and to control the laser transmission means so as to perform the desired operation.
The apparatus of the invention therefore allows remedial work to be carried out in situ without physically contacting the workpiece.
In a first embodiment, the tracking means comprises means to transmit a beam of visible light through the tube and out of the head, manual actuation means operable to move the head so as to direct the light beam to strike one or, sequentially, more than one desired point on the workpiece and wherein the processor is operable to record data representative of the position of the or each point.
The manual actuation means may comprise a joystick.
The laser transmission means may be adapted to selectively supply a lower power visible laser beam and a higher power laser beam for performing operations on the workpiece.
In another embodiment, the tracking means may comprise means to record the position of one or more selected points on the displayed image of the workpiece and wherein the processor is operable to relate the position of the or each point to the position of the head so as to actuate the control means to move the head to direct laser energy to the point, or, sequentially, to each point.
Conveniently, the viewing means comprises an optical scope integral with the tube.
Alternatively, the viewing means may comprise an optical scope removably located in the tube.
Preferably, the viewing means further comprises one of a camera and an image-to-video conversion device, and a display.
The viewing means may adapted for viewing laterally of the distal end of the tube.
Preferably, the control means and flexible coupling are selectively operable to move the head relative to the tube in three dimensions.
In one embodiment, the flexible coupling comprises spring means extending between the distal end of the tube and the head.
In another embodiment, the flexible coupling comprises at least one cylinder mounted between the tube and the head for pivotal movement relative to the tube, a sleeve attached to the head and axially moveable relative to the cylinder and spring means urging the head axially away from the tube.
The control means may comprise a plurality of pull elements secured to the head, and to the cylinder if present, and extending through the tube and means to retract and extend the pull elements.
Conveniently, the pull elements comprise wires.
The proximal end of each wire may be wound around a rotatable cylinder.
The flexible coupling may be encased in a flexible sleeve attached to the tube and to the head.
This flexible sleeve may be attached to the head and to the tube in a gas tight manner.
The means to transmit laser energy preferably comprises an optical fibre.
In one embodiment, the optical fibre terminates in the head and the head further includes means to focus a laser beam emitted from the optical fibre.
The focusing means may comprise a train of lenses and/or include an aspheric lens.
A protective screen is preferably provided in the head, distally of the focusing means.
Alternatively, the optical fibre may extends out of the head.
In this case, the distal end of the optical fibre may be shaped so as to emit a focussed laser beam from the optical fibre.
Alternatively, the distal end of the optical fibre may be shaped so as to emit a divergent laser beam from the optical fibre.
A laser filter may be provided to protect the viewing means from laser energy.
The viewing means may further include a filter to pass infra-red radiation only for display.
The tube and head are preferably, adapted to allow gas flow therethrough.
In this case, the apparatus may further comprise a gas supply for supplying pressurised gas or a mixture of gases to the tube and head.
Preferably, the gas is, or the mixture of gases includes, an inert gas.
The gas, or the mixture of gases, may include oxygen.
The apparatus may further comprise means to feed filler material through the tube and to dispense the filler material from the head.
In a another aspect the present invention also provides a method performing an operation on a workpiece at an inaccessible location utilizing the aforementioned apparatus, comprising the steps of positioning the tube with its distal end in the vicinity of the workpiece; gathering an image of the workpiece with the viewing means and displaying the image; identifying and recording the position of one or more selected points on the workpiece; and operating the processor to move the head and to supply laser energy through the tube so as to direct the laser energy to the point or, sequentially, to each point so as to perform a desired operation.
The identifying and recording step may comprise transmitting a beam of visible light through the tube and out of the head; adjusting the position of the head with manual actuation means so as to direct the light beam to strike a selected point on the workpiece; recording the position of the point and, optionally, repeating the process on one or more further points.
Alternatively, the identifying and recording step may comprise viewing an image of the workpiece on a display; marking the position of a point on the workpiece on the display; recording the position of the point and, optionally, repeating the process on one or more further points.
The invention will now be described in detail, by way of example only, with reference to the accompanying drawings in which: